June 13, 2011

In today's class we did pages 58, 43, 52 and 55

Page 58

1. true
2. false, thickness
3. false, closes
4. true
5. false, parallel
6. false
7. A

Page 43

1. 40 ohms
2. 3 A
3. no, the current 3A is less than 10A fuse
4. 40 ohms
5. 3A
6. No, 3A < 10A
7. 9.375 ohms
8. 12.8A
9. Yes
10. Increase value of one of the resistors

Page 52 -53

1. 2.5 ohms
2. 
   
3. 
   

b.)1 ohms ; 4W; 2A; 2V

2 ohms; 8W; 2A; 4V

c.)6 ohms; 6 W; 1 A; 6V

3 ohms, 12W, 2A, 6V

d.) 2 ohms; 4.5 W; 1.5A, 3V

2 ohms; 4.5 W; 1.5 A; 3 V

1 ohm; 9V; 3A; 3V

Page 55

1. b
2. c
3. d
4. a
5. a
6. b
7. b

June 9

Answers for circuits booklet

Page 48
1. 3A
2. 6ohms,0.5A
3. 12 ohms
4a. b
4b. a
4c. 4,6
4d. 5
4e. 4,6
4f. b
4g. b

Page 49
1a. 3A
1b. 6A
1c. All 3A EXCEPT for the two bottommost which the answer is 6A
2b. d
3a. 6V
3b. 3A,3A,6A
3b. 12A
3c. 0.5 ohms

Page 50
1.



2.



We also need to answer page 37,38 and 41

JUNE 8, 2011

In today's class we did a lab experiment from the green booklet about Circuits.
The materials that you need are:

• batteries
• alligator clip.
• light bulbs
• sockets

We did two kinds circuits. Thes are Series and Parallel Ciruits.

• This is one of the kinds of the circuits that we did;
  This one is called series circuit.
• With this kind of circuit if you loosen one of the bulbs espescially the one in between, all of the lights, turned off.
  
  
• Another type of series that we did is this one.
• It is called,parallel circuit.
• With this type of circuit, when you loosen up one of the bulbs. the current will still flow and the light did not turn off.
  
  
  
  
  The next blogger will be SAI.
  
  
  
  
  
  
  
  
  

june 6 2011

READ PAGES 15-20!!!

DO PAGES 48-50!!!

finish page 14

Answer keys:

page 29

1) P=v^2/R

= (3)^2/30

= 0.3 W

2) T=v/R

=3/30

=0.1 A

3)power varies inversely with resistance. as R of bulb increases the amount of power of the bulb increases

4) E(or W)=Pt

= (.3)(3600)

= 1000J

page 31

1. resistance- property of an object that determines how much current will flow through that object

factors- length of the wire cross sectional area temperature material the object is made of.

2. voltage is a potential difference in other words voltage is PE/ charge. current is the movement of charge due to potential difference. thus, voltage is nothing more than a difference in potential and does not necessarily create a current. given the proper conditions, voltage causes charge to move and when they do a current is created

3. R=v/I

since v is a constant and R is increasing, the circuit must be decreasing

4. they allow complex circuits to be graphically illustrated clearly and concisely

Electric Current Booklet!

Answers for pages 44, 45, 46

p. 44

1a. volts
b. voltage
c. current

2a. 1
b. 15
c. 1
d. narrow pipe,thin wire

p. 45

1. 1.5x10^-3 A
2. 4 A
3. 1.2 A
4. 4A
5. 1.5 x 10^-2 A -> 3.0 x 10^-2 A
6. 1000 Ω
7. 10 Ω
8. 100 V
9. Yes the resistance change, case 1: 240 Ω case2: 50 Ω

p. 46

1. R=pL/A, A=pL/R, A= (1.72 x 10^-8 Ω·m )(20 m) / (.10 Ω)
A= 3.44 x 10^-6 m^2

d= sqr(4A/π) d= 2.09 x10^-3 m

2. A= (0.25 x 10^-3 m)(1 x 10^-3m) A=2.5 x 10^-7 m^2

L= RA/p L=(1.5Ω)(2.7 x 10^-7 m^2) / (100 x 10^-8 Ω·m )
L= 0.38m

3. p=RA/L p= (0.04 Ω)(2 x 10^-6 m^2) / 5m
p= 1.6 x 10 ^-8 Ω·m

4. L= RA/p L= (3 Ω)(1.5 x10 ^-6 m^2) / (100 x 10^-8 Ω·m )
L= 4.5m

5. A = pL/R A= ( 55 x 10^-8 Ω·m )(.2m) / .10 Ω
A= 1.1 x 10^-7 m^2

d= sqr(4A/π) d = sqr((4 x 1.1 x 10^-7 m^2) / π)
d= 3.74 x 10 ^-4 m

NOTE:
Nichrome resistivity is 100 x 10^-8 Ω·m
Tungsten resistivity is 55 x 10^-8 Ω·m


We also need to answer the 2 questions on the bottom of page 14 on separate sheet of paper

The next one to scribe is ctc

June 2nd

Worked on Pages 44,45,46, and 48
Pages 5- 12

Notes:

An electric current is a flow of charged particles.
A conventional current is just a flow of a positive charge.
Charges can not be created or destroyed, but they can be seperated.
A resistor is a device designed to have a specific resistance.
Resistance is known as the ratio of potential difference to the current.
Temperature can increase resistance since a moving charge is affected by molecules, greater molecular motion would thus increase the resistance.

Formulas:

I = q/t
I is the conventional current measured in Amperes (A)
q is the charge measured in Coulombs (C)
t is the time measured in seconds (s)

P = IV
P is power measured in Watts (W)
V is the Potential Difference also reffered to as Voltage, it is measured in Volts (V)

R = V/I
R is the resistance, measured in ohms, the symbol omega (Ω) can be used to represent it.

R = pL/A
p is a constant(the resistivity of the metal) (Ω·m)
A is the crossectional Area (m^2)
L is the length of the material (m)

Useful Ratios to take note of:

R1/R2 = L1/L2
R1/R2 = A2/A1
R1/R2 = p1/p2

For P46

Nichrome wire resitivity at room temperature varies from 1.10 × 10−6 Ω*m to 1.5 × 10−6 Ω·m
Tungston wire resistivity at room temperature is 5.28 × 10−8 Ω·m